รบกวนผู้รู้หน่อยครับ โค้ดที่ผมเขียนมา มันเกิด Error ที่ .ExcuteNonQuery() .. The transaction is either not associated with the current connection or has been completed

Option Explicit On
Imports System.Text
Imports System.Data
Imports System.Data.SqlClient

Public Class frmCustomer
    ' Private Const conStr As String = "Data Source=HOME-PC\SQLSERVER;Initial Catalog=MusicTreading;Integrated Security=True"
    Private ReadOnly Property Conn() As SqlConnection
        Get
            Dim ConnToFetch As New SqlConnection(strCon)
            ConnToFetch.Open()
            Return ConnToFetch
        End Get
    End Property

    Public Function GetData() As DataView
        Dim sqlQry = "select * from Customer"
        Dim ds As New DataSet
        Dim dv As DataView
        Try
            Dim Comm As New SqlCommand()
            Dim da = New SqlDataAdapter()
            With Comm
                .CommandText = sqlQry
                .Connection = Conn
            End With
            da.SelectCommand = Comm
            da.Fill(ds)
            dv = ds.Tables(0).DefaultView
        Catch ex As Exception
            Throw ex
        End Try
        Return dv
    End Function

    Private Sub ShowColumnsHeads()
        If dgvCustomer.RowCount > 0 Then
            With dgvCustomer
                .Columns(0).HeaderText = "รหัสลูกค้า"
                .Columns(1).HeaderText = "ชื่อ"
                .Columns(2).HeaderText = "นามสกุล"
                .Columns(3).HeaderText = "ที่อยู่"
                .Columns(4).HeaderText = "หมายเลขโทรศัพท์"
                .Columns(5).HeaderText = "E-mail"
                .Columns(0).Width = 100
                .Columns(1).Width = 120
                .Columns(2).Width = 150
                .Columns(3).Width = 250
                .Columns(4).Width = 120
                .Columns(5).Width = 120

            End With
        End If
    End Sub
    Private Sub frmCustomer_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        dgvCustomer.DataSource = GetData()
        ShowColumnsHeads()
    End Sub

    Private Sub dgvCustomer_CellMouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles dgvCustomer.CellMouseUp
        If e.RowIndex = -1 Then Exit Sub
        With dgvCustomer
            txtCusID.Text = .Rows.Item(e.RowIndex).Cells("CusID").Value.ToString()
            txtCusName.Text = .Rows.Item(e.RowIndex).Cells("CusName").Value.ToString()
            txtCusLastName.Text = .Rows.Item(e.RowIndex).Cells("CusLastName").Value.ToString()
            txtCusAddress.Text = .Rows.Item(e.RowIndex).Cells("CusAddress").Value.ToString()
            txtCusPhone.Text = .Rows.Item(e.RowIndex).Cells("CusPhone").Value.ToString()
            txtCusEmail.Text = .Rows.Item(e.RowIndex).Cells("CusEmail").Value.ToString()
            txtCusName.Focus()
            txtCusName.SelectAll()
        End With

    End Sub

    Sub AutoID()


        Dim tmp As Integer
        Sql = "SELECT Max(CusID) From Customer"
        Try
            Call dbOpen()
            Com = New SqlCommand(Sql, Conn)
            reader = Com.ExecuteReader()
            tmp = reader.FieldCount - 1

            If tmp < 0 Then
                txtCusID.Text = "00001"
            Else
                While reader.Read
                    txtCusID.Text = ((CInt((reader(0)).ToString.Substring(1))) + 1).ToString("00000")
                End While
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
            MsgBox("Error Auto ID")
        End Try
    End Sub

    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        Call AutoID()
        txtCusName.Focus()
    End Sub

    Private Sub InsertData()
        If MessageBox.Show("คุณต้องการเพิ่มข้อมูลลูกค้าใช่หรืไม่", "คำยืนยัน", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
            tr = Conn.BeginTransaction

            With sb
                .Remove(0, sb.Length)
                .Append("insert into Customer (CusID,CusName,CusLastName,CusAddress,CusPhone,CusEmail)")
                .Append("values (@CusID,@CusName,@CusLastName,@CusAddress,@CusPhone,@CusEmail)")
                Dim sqlAdd As String
                sqlAdd = sb.ToString()

                With Com
                    .CommandText = sqlAdd
                    .CommandType = CommandType.Text
                    .Connection = Conn
                    .Transaction = tr
                    .Parameters.Clear()
                    .Parameters.Add("@CusID", SqlDbType.Char).Value = txtCusID.Text.Trim()
                    .Parameters.Add("@CusName", SqlDbType.VarChar).Value = txtCusName.Text.Trim()
                    .Parameters.Add("@CusLastName", SqlDbType.VarChar).Value = txtCusLastName.Text.Trim()
                    .Parameters.Add("@CusAddress", SqlDbType.VarChar).Value = txtCusAddress.Text.Trim()
                    .Parameters.Add("@CusPhone", SqlDbType.VarChar).Value = txtCusPhone.Text.Trim()
                    .Parameters.Add("@CusEmail", SqlDbType.VarChar).Value = txtCusEmail.Text.Trim()
                    .ExecuteNonQuery()
                End With
            End With
        End If
    End Sub

    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
        Call InsertData()
    End Sub
End Class

Option Explicit On
Imports System.Data
Imports System.Data.SqlClient
Imports System.Transactions
Imports System.Text

Module Module1
    Public Conn As New SqlConnection()
    Public Com As New SqlCommand()
    Public strCon As String = "Data Source=HOME-PC\SQLSERVER;Initial Catalog=MusicTreading;Integrated Security=True"
    Public ds As New DataSet()
    Public sb As New StringBuilder()
    Public Sql As String
    Public reader As SqlDataReader
    Public tr As SqlTransaction

    Public Sub dbOpen()
        With Conn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = strCon
            .Open()
        End With
    End Sub
End Module

 Dim tr As SqlTransaction 'ประกาศ
  tr = Conn.BeginTransaction() 'เรียกใช้

    ' Private Const conStr As String = "Data Source=HOME-PC\SQLSERVER;Initial Catalog=MusicTreading;Integrated Security=True"
    Dim ConnToFetch As SqlConnection
    
    Private ReadOnly Property Conn() As SqlConnection
        Get
            ConnToFetch = New SqlConnection(strCon)
            ConnToFetch.Open()
            Return ConnToFetch
        End Get
    End Property